[Lsr] Re: [Teas] Re: Re: Re: Re: Re: Re: Re: Re: [Green] 【Distributed Power-aware TE is Impossilbe】RE: RV: Call for adoption: draft-many-teas-power-steering-01 (Ends 2026-09-10)

[Tony Li <[e-mail]>]

Hi Aijun,


> Let’s assume the each headend synchronizes their necessary information, and the network utilization is almost same in two links.
> To achieve “network-wide” polarize effect,  we need to assure each headend calculate its CSPF computation in sequence, or there will be no deterministic results that they will select the same sleepable link.
>  
> Can anyone support the distributed Power-aware TE answer it?


Asked and answered.  To repeat:

Even if the PCPPS metric on two paths is identical, a difference in the network utilization, even if they are almost the same is enough to attract traffic to the higher utilization link.  This need not be done in sequence, as the attractive link will continue to attract more and more traffic.

Furthermore, as paths are periodically optimized, the polarization will continue, trying to fill the higher utlization path.

We do not claim that it is deterministic.  Indeed, it can never be, as the headends are not coordinated.  Fortunately, it does not need to be.


> And, if we dig more deeply, we should know CSPF calculate the path not merely on power-aware information, there is also other constraints for using the links.


As stated, all normal CSPF constraints are available.  This is standard TE, please see RFC 5305.


> How to coordinate these constraints within the headends, to move the traffic in synchronize out of some sets of links? 


The constraints do not need to be coordinated. The goal is to consolidate traffic within the bounds of the constraints and power-sleep components that are vacated.  If no components are vacated due to bandwidth or constraints, then nothing will be put into power-sleep.  This is by design.  The goal is to save power if possible, but not disrupting traffic is a higher priority.

Regards,
Tony